“Not all flesh is the same flesh; there is one flesh for humans, another for animals, another for birds, and another for fish.” ‭‭1 Corinthians‬ ‭15:39‬ ‭HCSB‬‬

Paul is trying to get to the point — there is a physical flesh and a spiritual flesh.

God is a creative God. He did not stop with one kind of flesh for all living things. He made the flesh of animals with a lot of fur. He made the flesh of the birds with feathers. He made the flesh of the fish with scales. And the flesh of us humans He made with some hair, some more and some less than others. Each flesh has a purpose whether it is for flight, water resistance, heat, or defense. The purpose God made for that flesh is what that flesh does. 

The animal kingdom doe not have the free will that we have. They completely obey God. We call this instinct. They do what comes naturally to them. But for us, our fleshly man was changed when our greatest, oldest, father ate the fruit from the Tree of Knowledge of Good and Evil. He, Adam, no longer was a flesh that obeyed God but became the father of all flesh that would be corrupted and would have to try to obey God. Obeying God no longer comes naturally to us but we have to choose to do it. What comes naturally is our sin nature.  

Because we have not inherited our spiritual flesh yet and still live in the physical flesh then God gave us His spirit in us so that we can and a spiritual force in us in the right direction. 

“Don’t you know that your body is a sanctuary of the Holy Spirit who is in you, whom you have from God? You are not your own, for you were bought at a price. Therefore glorify God in your body.”

‭‭1 Corinthians‬ ‭6:19-20‬ ‭HCSB‬‬

https://www.bible.com/72/1co.6.19-20.hcsb

“Don’t you yourselves know that you are God’s sanctuary and that the Spirit of God lives in you? If anyone destroys God’s sanctuary, God will destroy him; for God’s sanctuary is holy, and that is what you are.”

‭‭1 Corinthians‬ ‭3:16-17‬ ‭HCSB‬‬

https://www.bible.com/72/1co.3.16-17.hcsb

Our flesh may be corrupted but God has chosen to live with us. Why not honor God who is alive in you with the deeds of your flesh by making it conform to His will and not your own. After all, God made you for a purpose.